Acoustic stethoscope



April 20, 1965 R. CEFALY 3,179,204

ACOUSTIC STETHOS COPE Filled Aug. 24, 1964 2 Sheets-Sheet l FM4 f2 (RELATIVE RESPONSE IN DB) April 20, 1965 R. cEFALY 13,179,204

ACOUSTIC STETHOSCOPE Filed Aug. 24, 1964 2 sheets-sheet 2 MURMURS* HEART SOUND- FRICTION RUB-* RALES AMPHONIC BREATHING BRONCH IAL BREATH ING l l l I I l l 50 |00 200 300 400 600 800 lOOO (FREQUENCY IN CPS) (FREQUENCY IN GPS) United States Patent O 3,179,204 ACOUSTIC STETHOSCOPE Ralph Cefaly, 3905 Perry St., Brentwood, Md. Filed Aug. 24, 1964, Ser. No. 391,551 9 Claims. (Cl. 181-24) My invention is directed to improvements in acoustic stethoscopes.

Heretofore acoustic stethoscopes using diaphragms in their pick-up heads have not been eflicient for the useful range of approximately 20 to 1000 cps. which is a significant range for murmurs and heart sounds as well as some other human physical sounds. Unless the diaphragm moves readily it will not pick up the higher ranges of sounds. The diaphragm must have extreme flexibility yet must be stiff enough not to collapse.

An object of the invention is therefore to provide a stethoscope with a sound pick-up head and diaphragm that has a projecting protrusion in the diaphragm for contact with the body being sensed wherein the diaphragm is of relatively thin readily flexible material that has stiffening ribs formed therein to prevent collapse when used and that provides stiffness when pressure is applied yet will not materially reduce the sound pick-up vibratory characteristics necessary to adequately pick up sounds in the range of approximately 20 to 3000 c.p.s. without losing its etiiciency.

- A further object of the invention is to provide a stethoscope diaphragm that -is etlicient for picking up sounds in the range of approximately 20 to 3000 c.p.s. that may be repeatedly used Without destroying its sound pick-up qualities in this range and Without collapsing.

' Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specic example is given by way of illustration only and, while indicating a preferred embodiment of the invention, is not given by way of limitation, since various changes and modifications withinthe spirit and scope of the invention will become apparent to those skilled in the art .from this detailed description.

. diaphragm taken along line 4-4 of FIG. 1;

FIG. 5 is a graphic illustration of sound ranges for various studied sounds; andV FIG. 6 is a chart made on a graphic level recorder showing response in db versus frequency in cycles per second of the stethoscope V.according to this invention shown in full line and that of another stethoscope shown in broken lines. Y A

Throughout the description like reference numbers and characters refer to similar parts.

The stethoscope sound pick-up head is generally indicated at 10. A typical head portion 11 is formed with a central boss 12 having an axially extending sound-transmitting passage 13 therethrough that may be externally threaded at 14 for attachment to the usual flexible conduit (not shown) of the whole stethoscope.

The axis through the boss 12 and of the head is indicated by X-X in FIG. 2. The stethoscope sound pickup head is symmetrical about this axis X-X.

3,179,204 VPatented Apr. 20, 1965 ACe head is threaded to receive an internally threaded bezel ring 17 which has an upper inwardly extending lip portion 17a that overlies the face portion 16h of the head to secure the diaphragm generally indicated at 18 in place. The bezel ring 17 has a knurled annular protruding rim 17h integral therewith that may be, as shown, markedly narrower than the whole height of the bezel ring to afford the usual dinger grasp portion for installing and removing the same.

Reference is now made to the diaphragm 18 construction which is of relatively thin flexible material and may be polyester material such as is known under the tradenme Mylar. The material of which the diaphragm is made is of the order of .005 inch thick. Normally the diaphragm must be readily movable to pick fup the relative high frequencies. It must have extremely flexible characteristics yet be stiff enough to pick up sounds by contact through a contact portion and application of pressure. In the application of pressure stress is placed on the diaphragm and it must not collapse with repeated application of this pressure as applied in repeated use.'

The diaphragm 18 is circular and has an annular peripheral portion 19 lying in the plane Y-Y transverse to thev axis X-X and received on the face 16h of the head 11 and held down by the bezel ring 17.

In the particular diaphragm shown, the diameter is about 1% inches. A central vibration sensing portion 20 is of cup shape and lies adjacent and spaced outwardly of the transverse plane Y-Y and has a at bottom 20a and opens toward the plane YaY. An intermediate annular portion generally indicated at 21 lies between the annular peripheral portion 19 of the central sensing portion 2t). This intermediate annular portion 21 has a rst portion 22 which is a frusturn surrounding the central sensing portion 20 and 4it tapers gradually to its outer edge at 22a which lies adjacent the plane Y--Y and a second portion 23 -which is an annular reinforcing zone. These portions 22 and 23 are approximately of equal width in their radial extent. This second portion 23 has a plurality of uniformly spaced radially extending elongated stiftening pockets 23a. These pockets extend or open facing the transverse plane Y-Y and are on the same side of the plane as the central sensing portion 20 and the annular portion 22. q

In the diaphragm shown, the outer diameter, as stated above, is about 17s inches. The flat bottom portion 20a of the central sensing portion 20 has a diameter of about s/sinch and the rst annular portion 22 of the intermediate portion inclines at an angle A ofvabout 10 to the transverse plane Y-Y. The pockets 23a for a 1% inch diameter diaphragm are about g of an inch deep at their deepest portion and are approximately Ms inch long in their radial direction. The ends of the pockets 23a are of concave shape as indicated at 23b and 23C in FIG. 4. The cup shaped sensing protrusion 20 has a concave wall portion 20h as viewed from within the protrusion that joins its iiat bottom 20a with the upper adjacent edge of the frustum portion 22.

While the reinforcing zone 23 is shown with its pockets 23a facing as opening to the transverse plane Y-Y, it is within the scope of the invention that these reinforcing atraso-s p es flexible to pick up the relatively high frequencies. These high frequencies are considered to run up to about 300 c.p.s. in the heart range of frequencies and occasional heart murmurs ascending to as high as 1000 c.p.s.

A sound chamber 24 is provided between the diaphragm 1S and its floor 15 of the pick-up head 11. The readily exible diaphragm 18 picks up the vibrations, ilexes with the vibrations and transmitter through the sound chamber sound waves emitting from the throat 13 transversely disposed to the diaphragm 18.

Reference to FIG. 5 shows a chart of the frequency ranges of interest to the doctor and user of stethoscopes. These may be summarized as follows:

C.p.s. Main portions of heart sounds and murmurs 7-300 Lowest murmur frequency in one series 50 Murmur range-very rare, occasional ascending to 1000 c.p.s 120-160 Precardial friction rub 140-660 Rales 1Z0-1000 Amphonic breathing 24U-660 Bronchial breathing 240-1000 Murmur range 100-200 Note in FIG. 6 in the full line the performance of the stethoscope according to the invention compared with, see broken line, another considered ecient stethoscope. The stethoscope, as shown by the full line, amplifies particularly in the 100 to 300 c.p.s. range within which full murmurs and heart sounds as shown in FIG. 5 which are of prime importance for proper diagnostic purposes, The responses shown in FIG. 6 are on a relative scale running from -40 db to 0.

With this `diaphragm arrangement improvement of sounds transmitted has been definitely noted and for a range of about to 1000 c.p.s. in which lies the murmurs and heart sounds remarkable performance has been noted. Yet, with this readily flexible and relatively thin membrane for picking up sounds a reliable diaphragm has been provided that will withstand repeated use even in the higher frequency ranges.

I claim as my invention:

l. In an acoustic stethoscope having a diaphragm carrying sound-receiving head with a centrally disposed boss having a sound-transmitting passageway therethrough, a diaphragm receiving and securing means and an intermediate portion between the boss and the diaphragm receiving and securing means, said intermediate portion generally tapering from the diaphragm receiving portion to the central boss, the combination therewith of a diaphragm of circular shape and having an annular peripheral portion received on said receiving and securing means of the head and lying in a transverse plane extending generally perpendicular to a central axis through said boss, a central vibration sensing portion of cup shape lying adjacent and spaced outwardly of said transverse plane and having a flat bottom and opening toward said transverse plane, an intermediate annular portion between said annular peripheral portion and said central sending portion, said intermediate portion having a rst portion surrounding said central sensing portion and tapering gradually as a frustum and terminating adjacent said transverse plane anda second portion surrounding said rst portion and connected with said annular peripheral portion, said second portion having a plurality of uniformly spaced radially extending elongated stitfening pockets.

2. In an acoustic stethoscope according to claim 1 wherein said intermediate portion of the diaphragm lies on the same side of the transverse plane as said central sensing portion.

3. In an acoustic stethoscope according to claim l wherein said diaphragm is of readily llexible material of the order of about .005 inch in thickness.

4. ln an acoustic stethoscope according to claim l wherein said rst and second portions of the intermediate portion of the diaphragm are of approximate equal widths.

5. ln an acoustic stethoscope according to claim 4 wherein said diaphragm is approximately 1% inches in diameter and .005 inch thick said flat bottom of the sensing portion is approximately inch in diameter, said frustum portion of the intermediate portion inclines at approximately a 10 angle to said transverse plane and said radially extending elongated stiflening pockets are approximately '0/32 inch deep whereby to cover a pick up range from low to high frequencies in the range of approximately 20 to 3000 c.p.s.

6. A vibratory body for use in acoustical stethoscope having a head for sound pick up consisting of a circular sheet of readily flexible material ofthe order of about .005 inch in thickness having an annular peripheral portion for securement to the head, a central vibration sensing portion of cup shape lying adjacent and spaced outwardly of a transverse plane extending to include at least a part of said peripheral portion and having a flat bottom and opening toward said transverse plane, an intermediate portion between said annular peripheral portion and said central sensing portion, said intermediate portion having a first portion surrounding said central sensing portion and tapering gradually as a frustum and terminating adjacent said transverse plane and a second portion surrounding said first portion and connected with said annular peripheral portion, said second portion having a plurality of uniformly spaced radially extending elongated stiffening pockets extending on the same side of said transverse plane as said central sensing portion.

7. A vibratory body for use in acoustical stethoscopes according to claim 6 wherein said rst and second portions of the intermediate portion of the diaphragm are of approximate equal widths.

8. A vibratory body for use in acoustical stethoscopes according to claim 7 wherein said diaphragm is approximately 1% inches in diameter and .005 inch thick, said flat bottom of the sensing portion is approximately 5/s inch in diameter, said frustum portion of the intermediate portion inclines at approximately a 10 angle to said transverse plane and said radially extending elongated stitfening pockets are approximately 1%,2 inch deep whereby to repeatedly cover a pick up range from low to high frequencies in the range of approximately 20 to 3000 c.p.s. without deterioration.

9. A vibratory body of the character described in claim 8 wherein said elongated stiifening pockets open toward said transverse plane.

References Cited by the Examiner UNITED STATES PATENTS 2,439,665 4/48 Marquis 181--32 3,109,508 11/63 Cefaly 181-24 3,132,713 5/64 Seeler 181-32 LEO SMILOW, Primary Examiner. 

6. A VIBRATORY BODY FOR USE IN ACOUSTICAL STETHOSCOPE HAVING A HEAD FOR SOUND PICK UP CONSISTING OF A CIRCULAR SHEET OF READILY FLEXIBLE MATERIAL OF THE ORDER OF ABOUT .005 INCH IN THICKNESS HAVING AN ANNULAR PERIPHERAL PORTION FOR SECUREMENT TO THE HEAD, A CENTRAL VIBRATION SENSING PORTION OF CUP SHAPE ADJACENT AND SPACED OUTWARDLY OF A TRANSVERSE PLANE EXTENDING TO INCLUDE AT LEAST A PART OF SAID PERIPHERAL PORTION AND HAVING A FLAT BOTTOM AND OPENING TOWARD SAID TRANSVERSE PLANE, AN INTERMEDIATE PORTION BETWEEN SAID ANNULAR PERIPHERAL PORTION AND SAID CENTRAL SENSING PORTION, SAID INTERMEDIATE PORTION HAVING A FIRST PORTION SURROUNDING SAID CENTRAL SENSING PORTION AND TAPERING GRADUALLY AS A FRUSTUM AND TERMINATING ADJACENT SAID TRANSVERSE PLANE AND A SECOND PORTION SURROUNDING SAID FIRST PORTION AND CONNECTED WITH SAID ANNULAR PERIPHERAL PORTION, SAID SECOND PORTION HAVING A PLURALITY OF UNIFORMLY SPACED RADIALLY EXTENDING ELONGATED STIFFENING POCKETS EXTENDING ON THE SAME SIDE OF SAID TRANSVERSE PLANE AS SAID CENTRAL SENSING PORTION. 